US PATENT SUBCLASS 501 / 53
.~.~ Silica containing

Current as of: June, 1999
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501 /   HD   COMPOSITIONS: CERAMIC

1  DF  CERAMIC COMPOSITIONS {15}
11  DF  .~ Glass compositions, compositions containing glass other than those wherein glass is a bonding agent, or glass batch forming compositions {11}
53.~.~ Silica containing {3}
54  DF  .~.~.~> More than 90 percent by weight silica
55  DF  .~.~.~> 40 percent - 90 percent by weight silica {7}
73  DF  .~.~.~> Less than 40 percent by weight silica {2}

DEFINITION

Classification: 501/53

Silica containing:

(under subclass 11) Compositions containing silica (SiO2).

(1) Note. The silica is typically present in combination with metallic oxides, i.e., in the silicate, mixed silicate, or polysilicate form.

(2) Note. This subclass takes claims to silica containing glass compositions which do not specify the percent by weight content of the silica in the total composition. Where such content is specified, classification takes place into subclasses 54, 55+, or 73+.

(3) Note. In the subclasses indented hereunder, a disclosure of the weight percent of SiO2[end subscrpt] in the composition which is in the form of a range extending on both sides of the 40 percent and/or 90 percent limit recited in the titles of subclasses 54, 55, and 73, is classified or cross-referenced in such a way that an official copy appears in appropriate subclasses on both sides of that limit. For example, a disclosure of 28-42 percent SiO2 content is classified in subclasses 55+ and cross-referenced in subclasses 73+.